A vineyard’s exposure to wildfire smoke can affect the following year’s crop, as well as the current grapes.
The exposure of vineyards and grapes to strong, sustained smoke may result in wines that smell smoky, burnt, bacony, medicinal, or like an ashtray—all examples of what is commonly described as “smoke taint.” When tree wood burns, aroma compounds called volatile phenols are released. In the vineyard, these compounds can permeate the grape skins and rapidly bond with the sugars inside the grapes to form molecules called glycosides. Unfortunately, the effects of the smoke exposure are masked because the bonded phenols are indetectable by smell or taste. However, once grapes are fermented, the acidity in the resulting wine will begin to break these bonds, releasing the unpleasant aromas into the finished wine. Because “smoke taint” is absorbed into grapes on the vine through their skins and the vine’s leaves, both of which are removed during harvest and later during pruning, numerous studies confirm that smoke taint does not linger in the vine in a way that could affect future harvests.
While smoke tainted wine won’t harm the consumer, growers who suspect, or have tested for, smoke taint may choose not to make wine with grapes from affected vineyards. And although not making wine can have severe financial repercussions, the grapes can still be used in other ways. Grapes can be harvested directly onto the ground to decompose into natural fertilizer. Smoke-affected grapes are safe to use as a source of feed for livestock and for the production of neutral alcohol spirits. Smoke taint compounds can also be mostly removed during the distillation process (for example, in the production of brandy).